"해라체 is formal speech used with those who are the same rank or lower, but with no added degree of respect. Even though there’s no added respect, it wouldn’t be considered disrespectful to use 해라체 as long as it’s used appropriately.

Though not as common as 합쇼체, 해요체, or 해체, it’s still used frequently in modern-day Korea. It’s absolutely necessary, however, to master 해라체 because it’s used to quote other people. In other words, any time you want to say that someone else (including yourself) said something, it’s expected that the speech within the quotes is in 해라체. This is known as plain form in some Korean textbooks."